With the frequent occurrence of extreme weather such as typhoons and rainstorms, waterlogging has become one of the most important threats to global crop growth and production. Waterlogging limits plants’ access to oxygen and light, leading to disadvantageous changes in metabolism to disturb plant growth and development. To escape the damage of hypoxia or promote the diffusion of oxygen to submerged organs, plants respond to waterlogging stress by regulating their morphological structure, photosynthesis, respiration, energy metabolism, and endogenous plant hormone biosynthesis/signal transduction. The adventitious roots (AR), aerenchyma, and stem internode are the major target structure for waterlogging adaptation. The molecular mechanism of crop survival under waterlogging conditions and the key genes related photosynthesis, reactive oxygen species (ROS) homeostasis, and ethylene signal transduction are reviewed. We also elucidated recent advances in the study of interactions between various regulatory pathways and emphasized the important role of stress memory and cross-stress mechanisms in plant response to abiotic stress, indicating the importance of epigenetic modifications. On the basis of above, the research direction and focus of plants coping with waterlogging stress in the future are proposed. This review provides rich genetic resources and a theoretical basis for improving the genetic breeding of crop resistance to waterlogging.

Light signaling plays a substantial role in regulating plant development, including the differentiation and elongation of single-celled tissue. However, the identity of the regulatory machine that affects light signaling on root hair cell (RHC) development remains unclear. Here, we investigated how darkness inhibits differentiation and elongation of RHC in Arabidopsis (Arabidopsis thaliana). We found that light promotes the growth and development of RHC. RNA-seq analysis showed that light signaling regulates the differentiation of RHC by promoting the expression of specific genes in the root epidermis associated with cell wall remodeling, JA, auxin, and ethylene signaling pathways. Together, these genes integrate light and phytohormone signals with root hair development. Our investigation also revealed that the core light signal factor ELONGATED HYPOCOTYL 5 (HY5) directly interacts with the key root hair development factor ROOT HAIR DEFECTIVE6 (RHD6), which promotes the transcription of RSL4. However, CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) repressed RHD6 function through the COP1-HY5 complex. Our genetic studies confirm associations between RHD6, HY5, and COP1, indicating that RHD6 largely depends on HY5 for root hair development. Ultimately, our work suggests a central COP1-HY5-RHD6 regulatory module that integrates light signaling and root hair development with several downstream pathways, offering perspectives to decipher single-celled root hair development.

β-D-Xylosidases (BXLs) are members of glycoside hydrolase family 3. They play essential roles in cell wall remodeling, plant development, and abiotic stress responses. BXL gene families have been systematically characterized in several crop species. However, a comprehensive analysis of BXL genes in cotton (Gossypium hirsutum), a globally important fiber and oilseed crop, is still lacking. In this study, we performed a genome-wide identification of BXL genes in allotetraploid cotton. A total of 25 GhBXL genes were identified and classified into six phylogenetic clades. Gene structure and conserved domain analyses showed that all GhBXL proteins possess the characteristic tripartite GH3 domain architecture. Chromosomal distribution and synteny analyses indicated that the expansion of the cotton BXL family may be associated with whole-genome duplication and allopolyploidization. Promoter cis-element analysis detected stress-responsive regulatory motifs in the GhBXL promoters, including STRE, W-box, DRE core, and as-1 elements. Under PEG-simulated drought and salt stress, expression profiling, independently confirmed by qRT-PCR, showed distinct temporal response patterns among GhBXL members. Weighted gene co-expression network analysis (WGCNA) further identified GhBXL-8, GhBXL-9, and GhBXL-20 as hub genes in stress-responsive modules. Their co-expressed partners were enriched in transcription factors, kinases, and stress-related proteins. These findings provide a systematic foundation for understanding the evolutionary dynamics and functional roles of BXL genes in cotton. They also highlight candidate genes for future functional investigation.